It's the long, hot summer of 1944 in the Weequahic neighbourhood of Newark. Most of the country's young men are engaged overseas, but Bucky Cantor, a muscle-bound, 23-year-old PE instructor, is stuck at home on account of his dodgy eyes. Instead of aiding his nation in the fight against Hitler, his job for the summer is to oversee the welfare of a group of children, as director of one of the city's playgrounds. It's hardly the glorious role he wished for himself, but Bucky, who has a deep sense of honour, approaches his duties – at least at first – with unflagging dedication.

He is powerless to protect his charges, however, against another sinister threat: polio. That summer, in Roth's imagined history, the disease spreads through Newark with nearly as much ferocity as in the (real) epidemic of 1916. Soon, several boys in Bucky's care have died and Roth describes with great pathos Bucky's sombre tasks in the aftermath of these tragedies: the family visits, the consoling speeches to the remaining children in his care.

He expertly captures the climate of fear and hostility the epidemic engenders: suddenly, parents start turning on Bucky, accusing him of hygienic laxness, of letting the children "run around like animals up there". Unsurprisingly, when an escape route presents itself, in the form of a job at the country summer camp where his girlfriend teaches, Bucky takes it, despite admitting to himself that this is a shameful dereliction of his duty.

Roth's 32nd book marks a wonderful return to form after the far-fetched sexual escapades of The Humbling. This is vintage Roth: the story of a good man worn down – and finally ruined – by circumstance. Everything about it is perfectly judged: the way the crisis at home mirrors the larger horrors abroad; the way the epidemic assumes ethnic overtones (the disease is especially rife in the Jewish parts of Newark, prompting antisemitic speculation); the way the climate of fear produced by the polio subtly resonates with our own age's anxieties about terrorism. The writing throughout is flawless and the ending, when it comes, is both clever and profoundly moving.